Plastics sheeting or film is used to package a great number of products on modern packaging lines. Such packages may be made from relatively thin plastics film that may be either a single layer or multiple layers. Laminate films comprise layers of material such as thermoplastics, including polyethylene and polypropylene, paper or metal, including aluminium. An adhesion promoting layer is often introduced to allow deposition of a metal or to prevent problems associated with delamination. Ideally, the packaging material is as thin as possible for economic reasons whilst being sufficiently strong to withstand the packaging process and any subsequent mechanical stress, and still act as an effective barrier to prevent spoilage of the contents. The packaging material must be strong to prevent it opening prematurely but this may result in problems for the consumer because the package can be difficult to open without resort to cutting tools such as scissors or knives. If such tools are unavailable, the consumer may attempt to rip the package open or tear it with the teeth. The package is likely to tear open in a random direction, causing the contents to be spilled and often destroying the package so that it cannot be re-closed.
The problems associated with opening plastics packages are well known and various attempts have been made to overcome them. Often a notch is cut into the edge of the package so that tearing can be initiated from that point.
However, the consumer may need to use considerable force to tear the package and, more importantly, the direction of tearing cannot be controlled. This method is often employed for single use products such as sachets of shampoo or ketchup because the package cannot be easily re-closed once it has been opened. One method of controlling the direction of the tear is to embed a tear strip in the package. This is seen, for example, in wrappers for cigarette packs and bars of soap. A ribbon of material is wrapped around the product and adhered to the package, usually leaving a small excess of ribbon to protrude and act as a pull-tab. The consumer simply pulls the tab so that the ribbon of material unwinds and tears the packaging in the same direction. This solution is effective but costly since it requires additional materials and a more complicated packaging process, thereby raising production efficiency problems. A further solution is to include a plastics zipper within the package. This allows the package to be opened and closed easily but greatly increases the cost.